The goals of the Irradiation & Dosimetry Core are to provide precise ex-vivo (blood) and in-vivo (mice) irradiations with accurate dosimetry. The Core will provide: a) photon irradiations of both mice and blood, spanning a dose-rate range of 6 orders of magnitude (5 Gy/sec to 0.1 Gy/day), b) exposures of blood and mice to neutrons with an energy spectrum mimicking that of a nuclear detonation and to mixed neutron+photon fields, and c) partial body irradiations of mice (hemibody or whole thorax) using photons. Central to reliable and reproducible irradiation and dosimetry is an effective quality control system. The Irradiation & Dosimetry Core has in place a series of Standard Operating Procedures (SOP) covering operation and dosimetry both for our standard irradiation sources as well as the non-standard CMCR-specific irradiation sources, such as the VAriable Dose-rate External Cs-137 irradiatoR (VADER) and the Columbia IND-spectrum Neutron Facility (CINF). The Core will collaborate with the NIAID-wide Radiation Physics Core to ensure that these SOPs are in accord with the accepted irradiation procedures across NIAID-funded programs. While standard dosimetric techniques will be used for most experiments, the Core will use advanced customized technologies to address the challenges of some of the proposed irradiation modalities. Organ dosimetry and dose verification will be performed using a unique heterogeneous mouse phantom, microMOSFET dosimetry, and Gafchromic film. In-vivo dosimetry for long-term experiments in the VADER, where mice are not restrained, will be performed using encapsulated thermoluminescent detectors, injected subcutaneously.